Analysis of ink gelation and acid base relationship

Suzhou screen printing ink, KUNshan PCB screen printing ink, PCB screen printing material suppliers

Ink gelation problems in the early oil type (oxidation drying and osmosis drying type) ink is often encountered, and in solvent (volatile drying type) and water-based ink occasionally encountered. It must be known that the cause of gelatinization is very complex (including the printing ink manufacturing process, such as drying agent before and after adding and so on). With the development of science, the use of new materials, so that we strengthen the scientific theory of research, and the quality control of ink components. When the composition of today's ink structure has changed, then, all kinds of abuses will appear at any time, but will be controlled. The reasons for gelatinization are as follows:

1 ink system resin molecular weight is too large (viscosity is too high);

2. The solid component is too much (even if the viscosity is small resin binder is no exception);

3 ink system acid value is too high;

4. Pigment and filler with alkalinity;

5 desiccant content is too much or choose to add the order of inappropriate (such as ink production before and after production will appear two results);

6 ink system solvent, especially quick-drying solvent is too much;

From the above six reasons can be seen: the first two belong to the scope of physics, and for an experienced ink maker or packaging printing operator to avoid and easy to rule out. The last four causes belong to the same category of chemistry. We'll see it again as we explore the last four causes; Dispersion process temperature is too high, solvent volatilization, improper application of auxiliary additives may also cause ink acidification tendency. For example, rosin resin with molecular weight of only 330 will appear gelatinization, stacking and inking difficulties when using high pigment tank ink to produce solvent flexible quick-drying ink printing. In addition, we should also pay attention to the strong acid pigment carbon ink pigment and rosin acid value of the pros and cons. This was enough to justify acid [acid is electrophilic, is the electron acceptor (proton donor)] are nucleophilic alkali, is electron donor (proton acceptor), and the so-called amphoteric solvents resin (there is a mix of proton donor and proton acceptor water, alcohol, acid and cellulose nitrate, etc.), followed by a won't form hydrogen, The relationship between gelling and aliphatic hydrocarbon solvents and neutral and amphoteric pigments has long been evident. That is, when the acid-base characteristics of pigments and the acid-base characteristics of binders are not suitable, we can use a variety of resins and pigments, filler acid-base characteristics adapt to balance or select appropriate solvents to make up for or improve, which is a conventional remedy.